Asus A42-G55 Replacement Battery 14.4V 4400mAh Li-ion

Asus G55 Series — 14.4V Li-ion Replacement Battery (A42-G55)

This is a 14.4V, 4400mAh (63.36Wh) Li-ion replacement battery for the Asus G55 notebook lineup. It fits the G55VW-DH71-CA, G55XI361VW-BL, G55XI363VW-BL, and related G55 variants. The OEM part numbers it replaces are A42-G55, 0B110-00080000, and B056R014-0037.

• G55 platform fit: All G55 models in this compatibility list share the same 14.4V rail, connector pinout, and BMS handshake protocol. The cell pack communicates state-of-charge data through the same SMBus lines used on the original Asus battery, so the laptop recognises it without driver changes.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a G55VW unit. The BMS accepted the full charge cycle without tripping a protection cutoff, and the SMBus reported capacity within normal range across repeated cycles.
• First-cycle calibration on the G55: After fitting, run one full discharge down to the hibernate cutoff, then charge uninterrupted to 100%. The G55 BIOS uses this cycle to reset its battery learn table — skipping it leaves the health indicator reading inaccurate data carried over from the old cell.

Why the G55 BIOS flags a new battery as poor health immediately after swap

The G55 BIOS reads health status from EEPROM data stored during the previous battery's life. When a new cell goes in, that stored data doesn't match the fresh cell's charge profile, so the firmware flags it as degraded. This is a data mismatch, not a fault with the replacement cell. Running the full discharge-to-hibernate then uninterrupted charge cycle forces the BIOS to overwrite the old EEPROM learn data with values from the new cell. After one or two complete cycles, the health indicator corrects itself.

G55 shutting down abruptly at 20–30% charge shown

This happens when the fuel gauge IC hasn't yet calibrated against the new cell's discharge curve. The IC predicts remaining capacity from a curve built on the old cell, so the percentage shown doesn't match actual cell voltage. Under full CPU and display load, the cell hits its voltage floor before the OS-reported percentage reaches zero, triggering an immediate shutdown. Run two full discharge-to-hibernate cycles followed by a full uninterrupted charge each time — after that, the fuel gauge recalibrates and the shutdown threshold aligns with real cell voltage, typically stabilising above 10.8V at the cutoff point.